Chapter+22_Lecture+Spring2025

Course Information

  • Course Title: Biology 1220

  • Instructor: Dan McCarthy

  • Semester: Spring Semester 2025

  • Contact: dcmccarthy@cpp.edu

  • Office Hours: TBD

  • Required Material: Join our iClicker class

Studying for the Course

  • Importance of proactive study habits and participation.

  • Encouragement to remain focused despite distractions (e.g., texting in class).

Attendance and Participation

  • Policy Reminder: Instructor is aware of texting during class.

  • Message: Attention during lectures is crucial for learning.

Grading Breakdown

  • **Components: **

    • Lecture Exams: 50%

    • Mastering Biology Homework: 40%

    • In-Class Assignments and iClicker: 10%

  • Letter Grades:

    Percentage

    Letter Grade

    90 – 100%

    A

    88 – 89.99%

    A-

    85 – 87.99%

    B+

    74 – 84.99%

    B

    70 – 73.99%

    B-

    67 – 69.99%

    C+

    63 – 66.99%

    C

    60 – 62.99%

    C-

    50 – 59.99%

    D

    0 – 49.99%

    F

Introduction to Evolution

  • Key Concepts:

    • The theory of evolution by natural selection explains species change over time.

    • Central ideas debated include the immutability of species versus their ability to change.

Historical Perspectives on Evolution

  • Historic Theories:

    • Traditional views (Plato, Aristotle) advocated for fixed species types.

    • Plato's Typological Thinking: steadfast perfection of species.

    • Aristotle's Great Chain of Being: hierarchy from simple to complex organisms.

Lamarck's Theory of Evolution

  • Main Idea: Evolution as a progression up a chain; more complex organisms evolve from simpler ones through inheritance of acquired traits.

  • Critique: Contrasts with Darwin’s natural selection model by proposing that changes occur within individuals.

Darwin & Wallace: Key Contributors

  • Natural Selection:

    • Posited by Darwin and Wallace; suggests variation among individuals leads to differential survival and reproduction.

    • Population thinking emphasizes the role of population-level changes over linear progressions.

Evidence for Evolution

  • Types of Evidence:

    • Fossils document changes over time; extinction reveals species dynamics.

    • Transitional features show paths of evolutionary development.

  • Rapid Evolutionary Changes:

    • Observations include antibiotic resistance in bacteria and adaptations to climate change in various species.

Homology as Evidence

  • Three Levels of Homology:

    • Genetic, Developmental, Structural.

    • Examples include common amino acid sequences in different species indicating shared ancestry.

Natural Selection Mechanism

Darwin’s Four Postulates

  1. Variation exists within populations.

  2. Some variations are heritable.

  3. More offspring are produced than can survive.

  4. Certain heritable traits provide a survival advantage.

Misconceptions about Natural Selection

  • Individuals don’t evolve; populations do.

  • It’s not about 'progress' or 'betterment' of species; evolution is a response to environmental pressures that lead to adaptations.

Constraints on Natural Selection

  • Genetic Constraints:

    • Genetic correlation and pleiotropy may limit optimal trait development.

  • Fitness Trade-Offs:

    • Adaptation involves compromises between different traits.